Ethylene, due to its wide range usage in the manufacture of a number of different types of products (e.g., plastics, polymer, fibers, packaging materials, etc.), is the most commercially produced organic chemical in the world with a present global capacity of 334 billion pounds and the expectation to rise between 400 and 450 billion pounds within the next number of years. Other olefins, such as propylene and its derivatives, are also in increasing demand.
Historically, alkenes or olefins such as ethylene have been produced from petroleum feedstock through naphtha cracking. However, the naphtha cracking process requires a significant amount of energy and capital cost to yield the desired olefins. Due to the increased availability of natural gas (and thus ethane) in the United States, ethane has been increasingly used as feedstock for ethylene production. Conventional steam cracking plants accept ethane or naphtha as feed which are preheated and mixed with steam at very high temperatures (e.g., about 750-900° C.) in tubular reactors. Thus they are converted to low relative molecular mass alkenes. With ethane as feedstock in steam cracking, the following reaction takes place on ethane:C2H6=C2H4+H2 (Main reaction) ΔH°=137 kJ/molC2H6+H2=2CH4 (Side reaction)
Also, the products from steam cracking plants require complex separation trains to separate and recover methane, H2, propane, propylene, butane, butylene and steam. Therefore, steam cracking (both ethane and naphtha) is a very energy intensive process. Specific energy consumption (SEC) from steam cracking process is 17-21 GJ/ton ethylene. Approximately 70% of the production costs in typical ethane- or naphtha-based plants is contributed by the energy cost. Due to large scale of production world-wide, energy consumption for ethylene alone accounts for about 1% of the world's annual energy consumption. Moreover, steam cracking process currently accounts for approximately 180-200 million tons of CO2 emission world-wide (1.0-1.2 lb CO2/lb ethylene). Due to such large magnitude of production of ethylene, any reduction on the energy requirement will be highly impactful.
Accordingly, it would be desirable to provide a production process for ethylene (or other olefins) that utilizes ethane and is further more energy efficient in relation to conventional olefin production processes.